Lactate metabolism by peptostreptococcus elsdenii: Evidence for lactyl coenzyme a dehydrase

Baldwin, R.L.; Wood, William F.; Emery, R.S.

doi:10.1016/0304-4165(65)90084-x

Cited by 60 publications

(24 citation statements)

References 22 publications

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“…Nevertheless, studies indicate that there exist variants of the enzyme that show efficient performance under full aerobic conditions (e.g., ref. 35). …”

Section: A Systematic Methods To Locate Synthetic Carbon Fixation Pathmentioning

confidence: 99%

Design and analysis of synthetic carbon fixation pathways

Bar‐Even¹,

Noor²,

Lewis

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

431

394

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Carbon fixation is the process by which CO 2 is incorporated into organic compounds. In modern agriculture in which water, light, and nutrients can be abundant, carbon fixation could become a significant growth-limiting factor. Hence, increasing the fixation rate is of major importance in the road toward sustainability in food and energy production. There have been recent attempts to improve the rate and specificity of Rubisco, the carboxylating enzyme operating in the Calvin-Benson cycle; however, they have achieved only limited success. Nature employs several alternative carbon fixation pathways, which prompted us to ask whether more efficient novel synthetic cycles could be devised. Using the entire repertoire of approximately 5,000 metabolic enzymes known to occur in nature, we computationally identified alternative carbon fixation pathways that combine existing metabolic building blocks from various organisms. We compared the natural and synthetic pathways based on physicochemical criteria that include kinetics, energetics, and topology. Our study suggests that some of the proposed synthetic pathways could have significant quantitative advantages over their natural counterparts, such as the overall kinetic rate. One such cycle, which is predicted to be two to three times faster than the Calvin-Benson cycle, employs the most effective carboxylating enzyme, phosphoenolpyruvate carboxylase, using the core of the naturally evolved C4 cycle. Although implementing such alternative cycles presents daunting challenges related to expression levels, activity, stability, localization, and regulation, we believe our findings suggest exciting avenues of exploration in the grand challenge of enhancing food and renewable fuel production via metabolic engineering and synthetic biology. metabolic engineering | synthetic biology | photosynthesis | carboxylation | biological optimization I n the process of transforming sunlight into stored chemical energy, plants absorb approximately 10 times more CO 2 from the atmosphere than the total amount emitted by human activities globally (1). Moreover, agriculture, which is effectively a massive carbon fixation industry, makes use of the majority of cultivatable land on earth and accounts for most of the fresh water used by humanity (2). These figures point to the central role that carbon fixation by plants plays in our global ecological footprint. In nature, the factors limiting the growth of photosynthetic organisms vary among habitats and often include the availability of water, light, fixed nitrogen, iron, and phosphorus (e.g., ref.3). However, in agriculture today, the use of fertilizers and irrigation can make carbon fixation a rate-limiting factor. For example, many C3 plants have shown a significant increase in biomass when exposed to twice the atmospheric CO 2 concentration (4). Impressive growth enhancements have been demonstrated by addressing several biochemical limiting factors, related both to the light-dependent and light-independent reactions (5-9). For instance, tran...

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“…Nevertheless, studies indicate that there exist variants of the enzyme that show efficient performance under full aerobic conditions (e.g., ref. 35). …”

Section: A Systematic Methods To Locate Synthetic Carbon Fixation Pathmentioning

confidence: 99%

Design and analysis of synthetic carbon fixation pathways

Bar‐Even¹,

Noor²,

Lewis

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

431

394

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“…Since lactoyl-CoA dehydratase from C. propionicum is an extremely oxygen-sensitive enzyme, it may exist only under strict anoxic conditions. Due to misleading assays of putative lactoyl-CoA dehydratases under oxic conditions (Baldwin et al 1965;Fernandez-Briera and Garrido-Pertierra 1988), it has been accepted by many microbiologists that Escherichia coli is able to convert propionate to pyruvate via acryloyl-CoA. There is also no report of a complete β-oxidation of propionylCoA.…”

Section: Introductionmentioning

confidence: 96%

Propionate oxidation in Escherichia coli : evidence for operation of a methylcitrate cycle in bacteria

Textor¹,

Wendisch

Graaf

et al. 1997

Archives of Microbiology

177

185

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Escherichia coli grew in a minimal medium on propionate as the sole carbon and energy source. Initially a lag phase of 4-7 days was observed. Cells adapted to propionate still required 1-2 days before growth commenced. Incorporation of (2-13C), (3-13C) or (2H3)propionate into alanine revealed by NMR that propionate was oxidized to pyruvate without randomisation of the carbon skeleton and excluded pathways in which the methyl group was transiently converted to a methylene group. Extracts of propionate-grown cells contained a specific enzyme that catalyses the condensation of propionyl-CoA with oxaloacetate, most probably to methylcitrate. The enzyme was purified and identified as the already-known citrate synthase II. By 2-D gel electrophoresis, the formation of a second propionate-specific enzyme with sequence similarities to isocitrate lyases was detected. The genes of both enzymes were located in a putative operon with high identities (at least 76% on the protein level) with the very recently discovered prp operon from Salmonella typhimurium. The results indicate that E. coli oxidises propionate to pyruvate via the methylcitrate cycle known from yeast. The 13C patterns of aspartate and glutamate are consistent with the further oxidation of pyruvate to acetyl-CoA. Oxaloacetate is predominantly generated via the glyoxylate cycle rather than by carboxylation of phosphoenolpyruvate.

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“…The first is that acrylyl-CoA is generated endogenously, even though the presence of this molecule has only been documented in a few cases over and above those bacteria that catabolise DMSP such as those cases, described above, in Chloroflexus, Clostridium and some Archaea. It has also been predicted that acrylyl-CoA is formed from lactoyl-CoA in lactate metabolism [52]–[54], propionyl-CoA in propionate metabolism [55] and the β-oxidation pathway of glucose fermentation [56], and β-alanyl-CoA in β-alanine metabolism [57], but these suggestions have not been directly verified.…”

Section: Discussionmentioning

confidence: 99%

Screening of Metagenomic and Genomic Libraries Reveals Three Classes of Bacterial Enzymes That Overcome the Toxicity of Acrylate

et al. 2014

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Acrylate is produced in significant quantities through the microbial cleavage of the highly abundant marine osmoprotectant dimethylsulfoniopropionate, an important process in the marine sulfur cycle. Acrylate can inhibit bacterial growth, likely through its conversion to the highly toxic molecule acrylyl-CoA. Previous work identified an acrylyl-CoA reductase, encoded by the gene acuI, as being important for conferring on bacteria the ability to grow in the presence of acrylate. However, some bacteria lack acuI, and, conversely, many bacteria that may not encounter acrylate in their regular environments do contain this gene. We therefore sought to identify new genes that might confer tolerance to acrylate. To do this, we used functional screening of metagenomic and genomic libraries to identify novel genes that corrected an E. coli mutant that was defective in acuI, and was therefore hyper-sensitive to acrylate. The metagenomic libraries yielded two types of genes that overcame this toxicity. The majority encoded enzymes resembling AcuI, but with significant sequence divergence among each other and previously ratified AcuI enzymes. One other metagenomic gene, arkA, had very close relatives in Bacillus and related bacteria, and is predicted to encode an enoyl-acyl carrier protein reductase, in the same family as FabK, which catalyses the final step in fatty-acid biosynthesis in some pathogenic Firmicute bacteria. A genomic library of Novosphingobium, a metabolically versatile alphaproteobacterium that lacks both acuI and arkA, yielded vutD and vutE, two genes that, together, conferred acrylate resistance. These encode sequential steps in the oxidative catabolism of valine in a pathway in which, significantly, methacrylyl-CoA is a toxic intermediate. These findings expand the range of bacteria for which the acuI gene encodes a functional acrylyl-CoA reductase, and also identify novel enzymes that can similarly function in conferring acrylate resistance, likely, again, through the removal of the toxic product acrylyl-CoA.

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Lactate metabolism by peptostreptococcus elsdenii: Evidence for lactyl coenzyme a dehydrase

Cited by 60 publications

References 22 publications

Design and analysis of synthetic carbon fixation pathways

Design and analysis of synthetic carbon fixation pathways

Propionate oxidation in Escherichia coli : evidence for operation of a methylcitrate cycle in bacteria

Screening of Metagenomic and Genomic Libraries Reveals Three Classes of Bacterial Enzymes That Overcome the Toxicity of Acrylate

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